Method and means for protecting magnesium and magnesium alloys



Patented Jan. 21, 1936 UNITED STATES PATENT bl-FICE MAGNESIUM AND MAGNESIUM ALLOYS Josef Martin Michel, Bitterteld, Germany, a.-

signor, by mesne assignments,

Corporation,

- Development Delaware -to Magnesium a corporation of No Drawing.Application July 30, 1932, Serial No.

627,105. In G 6 Claims.

The present invention relates to a method and means for protectingmagnesium and magnesium alloys from the action of certain organicsubstances, and particularly of polyhydric alcohols and aqueoussolutions of same.

Recently, it has repeatedly been suggested, with success, to add to thewater employed as a cooling medium in internal combustion enginespolyhydric alcohols such as-glycol and glycerine, or to employ the saidsubstances as suchas cooling media so as to enhance the cooling eflectand reduce the danger of freezing under low temperature conditions.When, however, the said cooling compositions are employed in contactwith magnesium or magnesium alloys, which are frequently used as aconstruction material for various parts of internal combustion engines,it has transpired that the-said metals are occasionally attacked by thepolyhydric alcohol even at ordinary temperatures, and that such attackinvariably occurs at the elevated temperatures obtaining in the workingengine.

I have now observed that a small addition amounting to at least about0.1 percent of alkali fluorides to cooling media comprising a polyhydricalcohol reduces the corroding attack upon magnesium and magnesium alloysto a negligible quantity. I

The following table is illustrative of the comparative eifect of anaddition of alkali fluoride. The last column of the table gives thereduction in weight suffered, in the course of 24 hours, by 1 sq. meterof a sheet of magnesium alloy (composed of 6 per cent of aluminium, 1per cent of zinc, 0.3 per cent of manganese, balance being magnesium)when exposed to the action of variouscooling compositions containing apolyhydric alcohol, with and without the addition of an alkalifluoride,'the loss in weight, of course. being representative of thecorroding eflect.

ermany August 6, 1931 I claim:

1'. A method of preventing the corroding action, upon magnesium andmagnesium alloys, of a liquid consisting substantially of a polyhydricalcohol, which comprises incorporating in said liquid a minor quantityof an alkali fluoride.

2. A method of preventing the corroding action, upon magnesium andmagnesium alloys, of a liquid consisting of a. polyhydric alcohol, whichcomprises incorporating in said liquid a minor quantity, amounting to atleast about 0.1 per cent by weight of the total liquid, of an alkalifluoride.

3. A method of preventing the corroding action, upon magnesium andmagnesium alloys, of a polyhydric alcohol, which comprises incorporatingin said alcohol a minor quantity, amounting to at least about 0.1 percent by weight of the total liquid, of potassium fluoride.

4. A liquid cooling medium for internal combustion engines, incapable ofattacking magnesium and magnesium alloys, which comprises a majorquantity of a poly ydric alcohol and a minor quantity of an alkalifluoride. 5. A liquid cooling medium for internal combustion engines,incapable of attacking magnesium and magnesium alloys, which consistsessentially of a polyhydric alcohol and a quail- 0.1 per cent by weightof the total liquid.

6. A liquid cooling medium for internal combustion engines, incapable ofattacking magnesium and magnesium alloys, which consists of a polyhydricalcohol and a quantity of potassium fluoride amounting to at least 0.1per cent by weight of the total liquid. 1

JOSEF MARTIN MICHEL.

v tity of an alkali fluoride amounting to at least

